I am having issues with the electric surge brakes on my boat trailer. My understanding is that on the 5 pin flat wiring harness one of the pins (usually the blue wire) is connected to the back up light circuit and disengages the trailer brake solenoid that permits the trailer to be backed up. When testing this with a test light it appears as though no power is present (ground has been confirmed to be good). I have swapped out the 7 round to a 5 flat converter in an effort to rule out a bad converter but same issue exists.
Have not had this issue on my other tow vehicle (other brand).


Could there be a relay that is missing from the factory?


Thoughts / ideas / suggestions welcome


Oh yes, the truck is a 2014 F-150 4 x 4 XLT with factory tow package

 

My only suggestion, I hope it helps.

Troubleshooting 4 and 5-Way Wiring Installations | etrailer.com

 

Did your truck come with a factory tow package? It is power from the backup lights that is used to engage the lockout. There is a separate set of fuses for the trailer plug. You should be able to find the location in your owners manual.

 

I never had a flat 5 connector so excuse me if I'm wrong, but that seams off to me. I run 7 way on everything, even though I am only using 4 pins most of the time. The brakes should have nothing to do with backing up. I have never heard of that.

You will have to bear with me as I work on tractor, and tractor trailers for a living, and there are some differences I know.

Green and yellow are for turning.

Brown is tail and running.

blue is brakes.

white is ground

purple I think is the color for back up lights

and red is the aux power. (hot at all times)

I may have a few colors mixed up. They run them a bit different on tractor trailers, and they run a lot more stuff like ABS, GPS, ETC.

 

Is this something new???? lock out brakes?

Never in my life have I heard of such a thing on light duty vehicles. Does the truck apply power to the brakes when its not in gear?

I have been pulling trailers a long time, and this strikes me as weird. I have never used my brake controller either though. I don't need it do to the size, and weight of my truck.

 

Standard 7 way wiring color codes:

Black = 12v +
White = Ground
Blue = Electric Brakes
Yellow = Back Up Lights or Aux
Green = Tail Lights
Red = Left Turn/Stop
Brown = Right Turn/Stop

Standard 4 way color codes:

White = Ground
Brown = Tail Lights
Green = Right Turn/Stop
Yellow = Left Turn Stop

 

5 pin connectors are generally used on boat trailers with surge brakes. The 5th wire is connected to the backup lights. It locks out the brakes so you can back up the trailer. With out the lockout backing up puts the trailer brakes on.

 

Interesting...........I dont think I would like it though. Seams like a headache.

Did you have anyone in the truck holding the brake while the truck was in reverse to test the pins? On the newer trucks its harder to track down since for what ever reason we now need a relay to tell a rely, to tell a solenoid to open/close a switch. I would start with the fuses under the hood, and then move to relays. If both check out you may have a broken wire in the truck somewhere.

 

I'm here a day late and a dollar short -
Your problem is that our trucks are not wired for a 5 pin flat connector; they are wired for a 4 pin flat connector.
This wasn't a real problem for me in the past, when I was driving an F150 because I could plug the 5 pin flat from the trailer to the 4 pin flat on the truck and leave the 5th pin just hanging out. This meant if I was going to do any serious backing with the boat I had to get out and manually turn the brake lock out, but that was ok.
At one point I bought a 7 way round to 5 pin flat adapter, which seemed to work, but my lights started going wonky on the boat trailer. I thought something was wrong with the trailer wiring, but when I plugged directly into the 4 pin flat, all the lights started working again, so the round adapter was the culprit.
Now that I have the F250, the 4 pin flat is shaped in such a way that I cannot physically plug the 5 pin flat into it leaving the 5th pin hanging out.
This means I'm going to have to change to a 5 pin flat connector, or somehow use an adapter such as this one on e-trailer.com:
2012 Ford F-250 and F-350 Super Duty Custom Fit Vehicle Wiring - Curt
Whether you use an adapter or wire in a 5 pin flat, in order to make it work properly you are going to have to tap into the wire on the driver's side back up light. It should connect to the blue wire on the trailer's 5 pin flat connector.
Caution: don't let the blue wire confuse you. The blue wire that is traditionally used by the brake controller supplies power to actuate the electric brakes on a trailer when the brake pedal is applied. This blue wire gets it's voltage when the truck is in reverse and is intended to keep the hydraulic brakes from actuating.

 

I've used the 7 pin to 5 pin adapters for many years and never had an issue. They are literally plug and play.

 

Good to know, perhaps mine really did go bad.
Since I can't find a direct replacement for Ford's modular 7 plus 4 pin connector in the form of a modular 7 plus 5 pin connector, it looks like I'm going to have to get another 7 to 5 pin adapter and give it a try.
Thanks!

 

I recommendation is to replace the 5 flat with a 7way.

Yellow wire to red pin
Green wire to brown pin
Brown wire (s) to green pin
White wire to white pin
Blue wire to center pin


1)Cost of plug vs adapter is comparable,
2)one less set of connections,
3)one less item to keep track of,
4)you are not hacking up the oem wiring on your Ford
5)you now have clear directions on terminal / wiring codes if you didn't befor

I own a hitch shop....